Properties of Matter 7th Grade Science

Partner Up! Find a partner On the note card provided write down three characteristics you notice about your person that someone could use to distinguish them (these have to be things you can look at them to see) Put YOUR initials on the back of the card Turn this card in to Mrs. Weaver

Using only the characteristics on your card, try to figure out who your person is. When you think you know, raise your hand

What is a property? A property is basically a characteristic of matter that helps you to distinguish what it is

Types of properties Extensive properties depend on the amount Examples: mass or volume Intensive properties do not depend on the amount Examples: density and color

Physical properties can be measured without changing a substance’s identity. These include Color Density Volume Mass Boiling point Melting point Why are boiling point and melting point not considered chemical properties?

Chemical properties are properties that become evident during or after a chemical reaction (so the substance would be changed to figure these out). Examples include: Toxicity Oxidation Flammability Heat of combustion Enthalpy of formation Chemical stability radioactivity

Examples of properties Hydrogen gas is very flammable Sodium is highly reactive Mercury is nonreactive Fluorine reacts violently with water Radium, plutonium and uranium are radioactive

The smallest form of an element is an atom Draw an atom Identify proton, neutron, electron What is the nucleus? What makes up the nucleus? The smallest form of an element is an atom Pure elements are made up of the same type of atom

Atomic number metals Element symbol nonmetals Element name metalloids Atomic mass

Atomic number = the number of protons in the nucleus of an atom Atomic mass = the total number or protons and neutrons it contains; the amount of stuff in the nucleus You can figure out the number of neutrons by subtracting the atomic number from the mass number

Elements are grouped together on the periodic table by properties Elements are grouped together on the periodic table by properties. Some are more reactive than others. What makes them reactive are the electrons. These electrons also give elements different chemical properties like conductivity, crystals, and oxidation

The most reactive elements are alkali metals, alkali earth metals and halogens The least reactive elements are the noble gases

Atoms come together to form molecules These molecules stick together in something called a bond. Some bonds are stronger than others depending on whether electrons are lost, gained, or shared Water Sodium Chloride Xenon tetra-flouride